static F1<NanoHTTPD.IHTTPSession, WebSocket> dummyWebSocketFactory() {
  ret func(NanoHTTPD.IHTTPSession handshake) -> WebSocket {
    print("New WebSocket.");
    ret new WebSocket(handshake) {
      protected void onPong(WebSocketFrame pongFrame) { print("WebSocket pong"); }
      protected void onMessage(WebSocketFrame messageFrame) { print("WebSocket msg: " + messageFrame.getTextPayload()); }
      protected void onClose(WebSocketFrame.CloseCode code, String reason, boolean initiatedByRemote) { print("WebSocket close"); }
      protected void onException(IOException e) { printStackTrace(e); }
    };
  };
}